Various prior art devices are known for the purpose of controlling automotive engine no-load idling speeds. It is common to set such engines at the lowest possible speed to conserve fuel. However, should a power-consuming device such as an air conditioner be turned on at idle speed, the engine may stall.
Prior art devices include that shown in W. Maisch U.S. Pat. No. 4,724,811 wherein an electro-magnetic adjustment mechanism is used to adjust the position of a throttle valve in accordance with different operating parameters (e.g. temperature, pressure and speed). The valve itself adjusts to different conditions to artificially increase or decrease the flow of air supplied to the engine. Similarly, in H. Janetzke U.S. Pat. No. 4,658,783 there is shown a solenoid-operated by-pass valve used to augment the air supplied to the engine through the throttle valve.